Shareholders' Equity and Stock Compensation (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	May 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Shareholders Equity and Share-Based Payments [Line Items]
Stock repurchased during period (in shares)	225,000
Stock repurchased during period	$ 3,900			$ 5,943		$ 17,708
Share-based Compensation, Excluding Accelerated Compensation Cost		$ 1,200	$ 1,600	3,700	$ 4,700
Total income tax benefit recognized related to stock-based compensation		464	638	1,400	1,800
Total intrinsic value of options exercised		29	46	141	178
Cash received from exercise of stock options		233	142	463	778
Income tax benefits received		554	3,400	2,400	5,300
Employee Stock Option
Shareholders Equity and Share-Based Payments [Line Items]
Cash received from exercise of stock options		233	34	269	67
Total unrecognized compensation cost related to nonvested stock awards		7		$ 7
Expected recognized over a weighted-average period, years				5 months 19 days
Restricted Stock
Shareholders Equity and Share-Based Payments [Line Items]
Total fair value of restricted stock shares/units vested and released		632	6,900	$ 5,200	11,300
Total unrecognized compensation cost related to nonvested stock awards		12,700		$ 12,700
Expected recognized over a weighted-average period, years				1 year 9 months 18 days
Restricted Stock Units (RSUs)
Shareholders Equity and Share-Based Payments [Line Items]
Total fair value of restricted stock shares/units vested and released		770	$ 1,800	$ 811	$ 2,100
Total unrecognized compensation cost related to nonvested stock awards		$ 771		$ 771
Expected recognized over a weighted-average period, years				7 months 24 days